The present invention relates generally to valves and more particularly to a unitary valve capable of performing a multiplicity of functions.
The use of valves for controlling the application or flow of fluids under pressure are well developed in the industry. Such valves have many uses, among them, controlling the positions of various surfaces on aerospace vehicles, the positioning of various machines and parts thereof, as well as the control of various types of systems. The number and control functions which must be performed in fluid circuits by the associated valves is large and extremely diverse. As a result a correspondingly large and diverse number of different types of valves have been designed to meet the function demands in particular applications. The types of valves have ranged from exceedingly simple on/off valves to relatively complicated control valves.
In the prior art it has been customary to construct each valve separately in accordance with the particular function which is to be performed. That valve is then installed in the fluid system along with various other valves to complete the finished apparatus. The utilization of such a multiplicity of valves often leads to an apparatus which is relatively large and heavy and increases the overall complexity of the system, thereby reducing its reliability under many applications. In an attempt to meet these problems, others have provided kits consisting of valve parts which can be assembled thereby permitting a more simplified construction of valves having various functions. Examples of such prior art kits are shown in U.S. Pat. Nos. 3,613,715 and 3,960,166. Basically such kits include a housing, a sleeve and a spool with the housing and sleeve including ports therein for controlling fluid flow depending upon the type of spool inserted. Other types of prior art spool valves which are utilized to control fluid flow are shown in U.S. Pat. Nos. 3,070,124, 3,391,708, 3,707,984, 4,066,239 and 4,087,967.